1. Field of the Disclosure
The present disclosure relates generally to the field of long term evolution (LTE), and more particularly, to handling of an LTE data radio bearer (DRB) offloaded to a wireless local area network (WLAN).
2. Description of the Related Art
Current wireless technology efficiently utilizes the licensed frequency spectrum to provide maximum data rate to a user of a user equipment (UE). Even though advances in the wireless technology such as LTE networks have increased the performance and capacity of wireless networks, this alone may not be sufficient to meet the data rate demand of the future.
Third generation partnership project (3GPP) specifications provide mechanisms to meet the data rate demand of a UE, using means such as carrier aggregation (CA) or dual connectivity (DC) by adding radio resources to a UE. For example, a UE may be configured with component carrier #1 and component carrier #2, where both of these aggregated carriers are transmitted using LTE radio access technology (RAT). Integration and/or aggregation of multiple RATs using the DC framework, where an LTE RAT and a WLAN RAT are aggregated at a radio layer are being explored. Such multiple RAT aggregation enables the addition of radio resources to a UE from the unlicensed band along with radio resources in the licensed band, providing efficient and appropriate usage of the unlicensed spectrum. A WLAN radio working in the unlicensed spectrum for example, in the 2.4 GHz or 5.0 GHz band, may be aggregated if a UE is served by LTE carrier(s) such that aggregation of WLAN radio resources happens at the radio layer. A DC framework specified by 3GPP in Release-12 can be exploited such that a data radio bearer (DRB) established for a UE on an LTE carrier may be split below a packet data convergence protocol (PDCP) layer and offloaded to a WLAN over a standardized interface so that user plane packets (data packets) may be transmitted over an LTE air-interface and/or a WLAN air-interface respectively. An established DRB considered for offload may be either a downlink (DL) DRB and/or an uplink (UL) DRB.
If such offloading of user plane packets occurs at the PDCP layer, in accordance with an existing 3GPP standard, a wireless terminal (WT) node of a WLAN may be unable to understand the LTE quality of service (QoS) characteristics of the DRB for applying them for the data packets transmitted over the WLAN air interface. Thus, LTE QoS characteristics must be mapped to WLAN QoS characteristics for the DRB offloaded to the WLAN. Without the mapping, there may be difficulty in maintaining the expected QoS of a user, which effectively degrades the user experience.
Further, there is a need for a flow control mechanism to control data rate for offloaded data packets transmitted between an LTE node (eNB) and a WT node. Without the flow control mechanism, this may lead to congestion of user data packets (PDCP packet data units (PDUs)) transmitted between an LTE node and a WT node.